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Nguyen, Xuan Canh,Lee, Won-Woo,Amin, Amr Mohamed,Eo, Jae-Seon,Bang, Soo-Mee,Lee, Jong-Seok,Kim, Sang-Eun 대한핵의학회 2010 핵의학 분자영상 Vol.44 No.1
Purpose It is uncertain whether the tumor burden as assessed using FDG-PET has prognostic significance in newly diagnosed diffuse large B-cell lymphoma (DLBCL). The authors undertook this study to determine whether a parameter that reflects both FDG uptake magnitude and the greatest tumor diameter is a prognostic indicator in DLBCL. Materials and Methods Forty-two DLBCL patients (age, $57.4{\pm}15.5$ years; male/female=25/17; stage I/II/III/IV=5/17/10/10) who underwent FDG-PET before chemotherapy were enrolled. A lesion with the highest maximum standardized uptake value (MaxSUV) on the PET image was selected, and size-incorporated MaxSUV (SIMaxSUV) of mass was calculated as MaxSUV ${\times}$ greatest diameter (mm) on the transaxial PET image. Median follow-up duration was 20.0 months. Results Twelve (28.6%=12/42) patients experienced disease progression, and 10 (23.8%=10/42) died during follow-up. Among six variables [Ann Arbor stage, %Ki-67 expression, International Prognostic Index (IPI), MaxSUV, greatest diameter, and SIMaxSUV] investigated, only SIMaxSUV was found to be a single determinant of progression-free and overall survivals by multivariate analyses (p<0.05). Conclusion These results suggest that SIMaxSUV, a new FDG-PET parameter that incorporates FDG uptake magnitude and the greatest tumor diameter, may be a useful indicator of prognosis in untreated DLBCL.
Xuan Canh Nguyen,김선호,Shah Hussain,안종국,유예지,한해주,유주순,임채오,윤대진,정우식 한국식물학회 2016 Journal of Plant Biology Vol.59 No.1
Osmotic stress is induced by several environmental stresses such as drought, cold and salinity. Osmotic stress may finally leads to oxidative damage, ionic imbalance and growth inhibition in plants. Gene expression analyses indicated that ZAT10 transcription factor, a novel substrate of Arabidopsis MPKs, could be induced by environmental stresses that result in osmotic stress. As previously reported, ZAT10 overexpressing transgenic plants showed enhanced tolerance to osmotic stress. However, in contrast to previous report, a zat10 knockout mutant showed an osmotic stress sensitive phenotype. To determine the biological function of EAR domain and phosphorylation sites of ZAT10, we constructed two transgenic plants expressing two ZAT10 mutant proteins having EAR domain mutations (ZAT10EAR) and phosphorylation site mutations (ZAT10AA). The phenotype of zat10 was complemented by the expression of ZAT10EAR mutant, however not by the expression of ZAT10AA mutant, indicating that the phosphorylation sites in ZAT10 by MPKs are involved in stress tolerance but the EAR domain is not. In this report, we suggest that ZAT10 function as a positive regulator in osmotic stress tolerance and the phosphorylation of ZAT10 is required for its function in Arabidopsis.
Nguyen Nhan Thi,김선호,김경은,Bahk Sunghwa,Nguyen Xuan Canh,김민갑,홍종찬,정우식 한국식물생명공학회 2022 Plant biotechnology reports Vol.16 No.1
Jasmonic acid (JA) is a phytohormone that plays a central role in plant defense against necrotrophic pathogens. JA signal- ing stimulates the increase of cytosolic calcium ion (Ca2+) and implicates the activity of mitogen-activated protein kinases (MPKs). We previously characterized that Ca2+/calmodulin (CaM) activates MPKs by inhibiting a CaM-regulated dual- specificity protein phosphatase1 (DsPTP1) at the biochemical level. In this study, we reported that Ca2+/CaM-mediated DsPTP1 negatively regulates the resistance to necrotrophic pathogens through the inhibition of JA-responsive MPK6. To elucidate the physiological function of inhibiting DsPTP1 activity by Ca2+/CaM, we constructed transgenic plants over- expressing DsPTP1 wild type (DsPTP1WT OX) and CaM deregulated mutant (DsPTP1K166E OX). Interestingly, the MPK6 activity was significantly reduced in DsPTP1K166E OX plants in response to JA compared to DsPTP1WT OX plants. Moreover, transcript levels of JA-responsive gene PDF1.2 and VSP1 were also highly decreased in DsPTP1K166E OX plants compared to DsPTP1WT OX plants. Furthermore, DsPTP1K166E OX plants showed more susceptibility to necrotrophic pathogens than DsPTP1WT OX plants. Conclusively, these results suggest that Ca2+/CaM activates the JA-responsive MPKs by inhibiting DsPTP1 for the resistance to the necrotrophic pathogen
박형철,Xuan Canh Nguyen,Sunghwa Bahk,Byung Ouk Park,김호수,Min-Chul Kim,Hans J. Bohnert,정우식 한국식물생명공학회 2016 Plant biotechnology reports Vol.10 No.6
Phosphorylation of substrate proteins by mitogen-activated protein kinases (MPKs) determines the specific cellular responses elicited by a particular extracellular stimulus. However, downstream targets of plant MPKs remain poorly characterized. In this study, 29 putative substrates of AtMPK3, AtMPK4 and AtMPK6 were identified by solid-phase phosphorylation screening of a k phage expression library constructed from combined mRNAs from salt-treated, pathogen-treated and mechanically wounded Arabidopsis seedlings. To test the efficiency of this screening, we performed in vitro kinase assay with 10 recombinant fusion proteins. All proteins were phosphorylated by AtMPK3, AtMPK4 and AtMPK6, indicating the efficiency of this screening procedure. To confirm phosphorylation of isolated substrates by plant MPKs, we performed in-gel kinase assays. All test substrates were strongly phosphorylated by wounding or H2O2-activated AtMPK3 and AtMPK6. Three substrates, encoded by genes At2g41430, At2g41900, and At3g16770, were strongly phosphorylated, suggesting a function as AtMPK substrates. The type of screening provides a powerful way for identifying potential substrates of MAP kinases responsive to biotic and abiotic stresses.
안종욱,Nguyen Xuan Canh,김선호,Bahk Sunghwa,강호빈,Le Anh Pham Minh,박재민,RAMADANYZAKIYAH,김상희,Park Hyeong Cheol,정우식 한국식물생명공학회 2022 Plant biotechnology reports Vol.16 No.6
Flavonoids have a variety of biological functions including UV protectant, antioxidant, allelopathy and auxin transport inhibitor in plants. In addition, favonoids are implicated in defense response against pathogens. In this study, we found that kaempferol, a kind of favonol, induces bacterial pathogen resistance. In addition, we identifed the signaling pathway to explain how kaempferol can induce pathogen resistance in Arabidopsis. We showed that kaempferol upregulates the transcription of two pathogenesis-related (PR) genes. Interestingly, the monomerization and nuclear translocation of NPR1, a key regulator of PR gene expression, was induced by kaempferol through the accumulation of salicylic acid (SA). Furthermore, we found that the kaempferol-induced monomerization of NPR1 is mediated by the activation of MPK3 and MPK6. Taken together, this study suggests that kaempferol induces pathogen resistance by both SA and MPK-dependent signaling pathways in Arabidopsis.
Optimized phos-tag mobility shift assay for the detection of protein phosphorylation in planta
Hussain, Shah,Nguyen, Nhan Thi,Nguyen, Xuan Canh,Lim, Chae Oh,Chung, Woo Sik The Korean Society of Plant Biotechnology 2018 식물생명공학회지 Vol.45 No.4
Post-translational modification of proteins regulates signaling cascades in eukaryotic system, including plants. Among these modifications, phosphorylation plays an important role in modulating the functional properties of proteins. Plants perceive environmental cues that directly affect the phosphorylation status of many target proteins. To determine the effect of environmentally induced phosphorylation in plants, in vivo methods must be developed. Various in vitro methods are available but, unlike in animals, there is no optimized methodology for detecting protein phosphorylation in planta. Therefore, in this study, a robust, and easy to handle Phos-Tag Mobility Shift Assay (PTMSA) is developed for the in vivo detection of protein phosphorylation in plants by empirical optimization of methods previously developed for animals. Initially, the detection of the phosphorylation status of target proteins using protocols directly adapted from animals failed. Therefore, we optimized the steps in the protocol, from protein migration to the transfer of proteins to PVDF membrane. Supplementing the electrophoresis running buffer with 5mM $NaHSO_3$ solved most of the problems in protein migration and transfer. The optimization of a fast and robust protocol that efficiently detects the phosphorylation status of plant proteins was successful. This protocol will be a valuable tool for plant scientists interested in the study of protein phosphorylation.
Optimized phos-tag mobility shift assay for the detection of protein phosphorylation in planta
Shah Hussain,Nhan Thi Nguyen,Xuan Canh Nguyen,임채오,정우식 한국식물생명공학회 2018 JOURNAL OF PLANT BIOTECHNOLOGY Vol.45 No.4
Post-translational modification of proteins regulates signaling cascades in eukaryotic system, including plants. Among these modifications, phosphorylation plays an important role in modulating the functional properties of proteins. Plants perceive environmental cues that directly affect the phosphorylation status of many target proteins. To determine the effect of environmentally induced phosphorylation in plants, in vivo methods must be developed. Various in vitro methods are available but, unlike in animals, there is no optimized methodology for detecting protein phosphorylation in planta. Therefore, in this study, a robust, and easy to handle Phos-Tag Mobility Shift Assay (PTMSA) is developed for the in vivo detection of protein phosphorylation in plants by empirical optimization of methods previously developed for animals. Initially, the detection of the phosphorylation status of target proteins using protocols directly adapted from animals failed. Therefore, we optimized the steps in the protocol, from protein migration to the transfer of proteins to PVDF membrane. Supplementing the electrophoresis running buffer with 5 mM NaHSO3 solved most of the problems in protein migration and transfer. The optimization of a fast and robust protocol that efficiently detects the phosphorylation status of plant proteins was successful. This protocol will be a valuable tool for plant scientists interested in the study of protein phosphorylation.
New Alkaloids and Anti-inflammatory Constituents from the Leaves of Antidesma ghaesembilla
Van Kiem, Phan,Cuong, Le Canh Viet,Trang, Do Thi,Nhiem, Nguyen Xuan,Le Tuan Anh, Hoang,Tai, Bui Huu,Huong, Le Mai,Van Minh, Chau,Lee, Taek Hwan,Kim, Sun Yeou NATURAL PRODUCT COMMUNICATIONS 2017 Natural product communications Vol.12 No.1